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Topic: "LightningStorm" VTTC project (Read 4207 times)

Hello all! This is my last VTTC project. This project started 3 years ago, and now finally assemble of generator unit case is started.The objective of the project - to build a powerful vacuum tube Tesla coil on the basis of soviet metal-glass high-power air-cooled tetrode GU-39B-1. This tube is capable to dissipate at the plate power around 6kW. And its output power is 13kW.It was made the plate and filament transformers. The filament transformer provides 6,6V and 100A. Plate transformer is wound on the base of the output transformer of the high power tube audio amplifier UPV-1,25 (russian УПВ-1,25) used two GU-81M tube in push-pull output stage. Its core is made up of steel plates of thickness 0.35 mm (core sectional area of 49cm^2). It provides voltage 5kV and 2A peak сurrent (nominally 1,5А)In the power supply used level shifter with eight 1uF 16KV capacitors and homemade diode pack at 50kV and 3a. All ceramic capacitors in circuit - soviet K15U-1 or K15U-2 type.The tube installed in a steel cylinder with polyamide insulator at the bottom. Centrifugal fan "bahcivan aorb" (BRDS 180-60, 1200 m³/h) is used to cool the tube. Tube operates in triode.The secondary winding contains 800 turns of 1mm copper wire on 160x800mm PVC pipe. Epoxy coating. 20x5cm (now is 30x10cm) aluminium toroid is installed.The primary is a 35 turns of 4mm copper wire on 250x500mm PVC pipe. Taps on each turn, starting with the 28th turn. Winding height is 28cm. MMC capacity is 2nF (4x470pf).Feedback winding has 14 turns of 1.5mm copper wire (taps of the first 5 turns). Located above the primary winding. Grid leak circuit is 200 Ohm and 14nF.Tesla Coil working in staccato mode. In the cathode circuit installed triac, which is controlled by circuit in 555 timers (based of the staccato cotroller of Steve Ward).At this moment VTTC gives streamers up to 1.5m length. The length of the streamers is limited to the power of the plate transformer and power mains capability (mains 230V 50Hz, current consumption up to 80A).

The principle of the QCW and the VTTC is the same. Historically, the VTTC is the first QCW. In the tube coil, the width of the radio pulse is determined by the frequency of the AC mains and is 20ms (for 50hz). In the transistor coil, we can set the pulse width ourselves.

The form of the discharges in my case depends on the resonance frequency of the secondary. In my secondary it is 250kHz, which causes the discharge like SGTС or DRSSTC. Sword-like discharges need over 400khz (better 600 and over).

Wow that is an absolutely record breaking spark length for a VTTC, I think only Dr. Spark and RogerInOhio has been near those lengths for a VTTC.

Thank you! My coil will be one of the few, brought to the state of the finished product. Ahead of the manufacture of the power supply (it's also a control panel)

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Is the GU-39B tube really easy to drive since you can do with just 5 windings on the feedback coil, or is it because the power output is so great that you are well below the normal 15-20 turns?

In the first post I wrote that the whole winding of 14 turns, taps from the last five. In fact, the entire winding is used, all 14 turns. The tube is quite difficult to drive, so the resistor in the gridleak is only 200 ohms.

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How are the temperatures on the secondary/primary/feedback coils and the tube? I guess all the good study Russian capacitors are stone cold

Temperatures of most structural elements are small. Nothing is very hot. The temperature of the secondary and primary windings does not differ from the air temperature. Maybe a little warmer.

Looks very good, but how is the creepage distance on the inside of that feed-through? The outer part looks to be fairly long and will be fine for 30kV, this is your tank capacitor rating, but not likely your circulating tank voltage, however it does look like its much smaller distance from the copper band to the mounting screws on the inside.